Desertification Evolution And Driving Force Analysisi In The Southeastern Edge Of Mu Us Sandy Land

Desertification is the land degradation in arid,semi-arid and partially semi-humid areas caused by human overuse or adverse natural conditions.Land desertification causes sandstorm activities and sand dunes in the original non-desertified areas,endangers the surrounding ecological environment and human social activities,and also encroachs people's production and living space.Since modern times,the desertification in China has been generally improved,but there is still a development trend in a few areas,so the prevention and control of desertification is still urgent.Remote sensing and geographic information technology have been widely used in monitoring desertification evolution and driving force analysis.In this study,the southeast edge of The Mu Us sandy land area is taken as the research area,Based on MODIS NDVI data from 2000 to 2018,vegetation index method was used to invert vegetation coverage to classify desertification types and analyze the spatial pattern and evolution characteristics of desertification.In addition,the natural and economic index data are widely obtained,the principal component analysis method is used to establish the land vulnerability assessment system,the land vulnerability assessment is conducted based on the GIS analysis function,and the land vulnerability situation of the study area is divided.Finally,combining natural and economic factors,the semi-quantitative method of correlation analysis was used to analyze the desertification degree and related indicators,and the main driving forces of different regions were analyzed.The main conclusions are as follows:(1)The analysis and study on the spatial and temporal distribution and evolution of desertification found that the non-desertification land area accounted for the largest proportion,reaching 62.91%,concentrated in the eastern part of the study area;Severe and moderate desertification is mainly distributed in the southwest of Shenmu city and the west of Yuyang District.From 2000 to 2018,the southeast edge of The Mu Us sandy land showed an increasing trend of non-desertification and mildly desertification,and the potentialdesertification land showed the largest reversal range,with the land taking up 84.35% of the total area showing different degrees of improvement.The center of gravity of all desertification types shifted to the northeast on the whole,and the desertification in the study area showed a reversal trend,among which Shenmu city had the best recovery condition and Dingbian County was the worst.(2)The research results of land vulnerability show that: under the influence of natural conditions and economic development,there is an obvious difference in the land vulnerability in the southeast margin of The Mu Us sandy land.The moderately and severely fragile land area in the southeast margin of the Mu Us sandy land is relatively large,up to about 50% at most.The regions with high vulnerability were mainly located in the east of the study area,while the regions with low vulnerability were mainly distributed in the west of the study area,concentrated in Dingbian County.In the central part of the study area and in the southern part of Jingbian County,mildly fragile and non-fragile lands are scattered and distributed,which have been improving year by year and expanding in scope.This may be because urban and river factors are conducive to the improvement of land conditions and the improvement of land vulnerability.(3)The driving force of desertification is mainly reflected in the following aspects:natural factors,except the increase of vegetation and rainfall,have small changes;economic factors mainly radiate outward from cities;in recent years,GDP,population density,night lights and other data have increased as a whole.Jingbian county and Dingbian County are mainly affected by air temperature factors,and the lower air temperature are not conducive to the reversal of land desertification.Vegetation was mainly applied in Shenmu city and Yuyang District,which was beneficial to land improvement.Economic factors mainly affect the surrounding areas with cities as the center,especially Shenmu city and Yuyang District.and on the whole,all factors are positively correlated to the improvement of land vulnerability,which is conducive to the recovery of desertification.In addition,since the launch of the policy of Returning Land from Farming to Forest(grass)policy in 1999,about 508 million mu of afforestation has been completed,and the grassland and forest land cover area has significantly increased,greatly promoting the improvement of ecological environment.